Derrick Jensen is primarily an advocate for indigenous peoples and wild nature, and an opponent of civilization, rejecting the notion that it can ever be an ethical or sustainable model for human society. He describes the linguistically and historically defensible definition of civilization[7] as "a culture — that is, a complex of stories, institutions, and artifacts — that both leads to and emerges from the growth of cities (civilization, see civil: from civis, meaning citizen, from Latin civitatis, meaning state or city),"[8] and the definition of city as a group of "people living more or less permanently in one place in densities high enough to require the routine importation of food and other necessities of life."[8] He explains that, by such definitions, civilizations and cities are both unsustainable:

Two things happen as soon as you require the importation of resources. One of them is that your way of living can never be sustainable, because, if you require the importation of resources, it means you've denuded the landscape of that particular resource, and, as your city grows, you’ll denude an ever-larger area. [...] And the other thing it means is that your way of life must be based on violence, because if you require the importation of resources, trade will never be sufficiently reliable because, if you require the importation of resources and the people in the next watershed over aren't going to trade you for it, you're going to take it.

An outspoken critic of human supremacy, Jensen adheres to a form of non-anthropocentrism: perhaps, ultimately, ecocentrism. First, his ethics advocates for humans to actively support the flourishing of entire natural communities and their many individual species, rather than the flourishing of humans alone. Second, his ethics extends the status of personhood to all organisms and ecosystems,[9] particularly including non-human animals and plants (for example, in an article on water management, he refers to "both human people and fish people").[10] His view, which moves central moral focus away from civilized humans, also names and castigates some of the values most championed by modern civilization, including technological advancement, economic growth, the inevitability of progress, and sustainability as seen through the lens of "development". Jensen advocates for a human way of life that is harmonious in a truly ecological sense, and is thus lastingly sustainable, such as the diverse ways of life historically exhibited by many Native American and other indigenous, non-civilized cultures. He also claims that "the fundamental difference between Western and indigenous ways of being is that even the most open-minded Westerners generally perceive listening to the natural world as a metaphor, as opposed to the way the world really is."[11] While indigenous peoples understand the world as consisting of other beings with whom we can enter into relationship, he argues, Westerners believe that the world consists merely of objects or resources to be exploited or used.

Jensen argues that the extreme pervasiveness of dysfunctional and antisocial civilized behaviors indicates that they are diagnostic symptoms of the greater problem of civilization itself. His analysis often compares the culture's abuses on the macro-scale through the microcosmic lens of domestic abuse and violence, intimately noting the connections between abusive personal relationships and the oppressive, expansionist culture as a whole. His discourse often, thus, explores the psychopathology of the entire modern society towards a conclusion that civilization and its global, industrial economy is fundamentally at odds with and obliterating healthy relationships, the natural environment (including numerous forms of life and their habitats), and indigenous ways of life. Accordingly, he urgently exhorts readers and audiences to help bring an end to industrial civilization, promoting its dismantling by any means necessary,[12] thus challenging pacifism, since he believes that violence may be justified at times, particularly as a form of self-defense or resistance against oppression. In A Language Older Than Words and also in an article entitled "Actions Speak Louder Than Words", Jensen states "Every morning when I awake I ask myself whether I should write or blow up a dam. I tell myself I should keep writing, though I'm not sure that's right".[13] Inspired by the potential for success of the crushed Warsaw Ghetto Uprising (when compared to the inevitable annihilation of Warsaw's non-rebelling Jews) and his being attacked by various mother animals in perceived defense of their babies,[14] Jensen most highly supports the type of violence used by oppressed people and wild creatures, who he feels have demonstrated it as a viable strategy against even the most powerful enemies. Jensen has clarified, however, that "I get accused of being the 'violence guy'... but I don't ever think that's really fair, because I really consider myself the 'everything guy', that I want to put everything on the table and talk about all forms of resistance.... We can certainly parse out cases where we think it's appropriate to have militant response or non-militant response."[2]

A Language Older Than Words uses the lens of domestic violence to look at the larger violence of western culture. The Culture of Make Believe begins by exploring racism and misogyny and moves to examine how this culture’s economic system leads inevitably to hatred and atrocity. Strangely Like War is about deforestation. Walking on Water is about education (It begins: "As is true for most people I know, I’ve always loved learning. As is also true for most people I know, I always hated school. Why is that?").[21]Welcome to the Machine is about surveillance, and more broadly about science and what he perceives to be a Western obsession with control.

Endgame is interspersed with what he describes as the inherent unsustainability of civilization. In this book he asks: "Do you believe that this culture will undergo a voluntary transformation to a sane and sustainable way of living?" Nearly everyone he talks to says no. His next question is: "How would this understanding — that this culture will not voluntarily stop destroying the natural world, eliminating indigenous cultures, exploiting the poor, and killing those who resist — shift our strategy and tactics? The answer? Nobody knows, because we never talk about it: we’re too busy pretending the culture will undergo a magical transformation." Endgame, he says, is "about that shift in strategy, and in tactics."[22]

Most of Jensen's writing uses the first-person and personal experiences to construct arguments. His books are written like narratives, lacking a linear, hierarchical structure. They are not divided into distinct sections devoted to an individual argument. Instead, his writing is conversational, leaving one line of thought incomplete to move on to another, returning to the first again at some later point. Jensen uses this creative non-fiction style to combine his artistic voice with logical argument. Jensen often uses quotations as reference points for ideas explored in a chapter. (For example, he introduces the first chapter of Walking on Water with a quote from Jules Henry's book Culture Against Man.)[23]

In 2008, Jensen wrote Thought to Exist in the Wild (with photographs by Karen Tweedy-Holmes), which discussed the keeping of animals in zoos on both a physical and philosophical level. The book won the 2008 grand prize for the Eric Hoffer Award for Books.

Jensen co-wrote the book Deep Green Resistance: Strategy to Save the Planet with Lierre Keith and Aric McBay. Jensen's contribution consists of end-of-chapter responses to common queries he gets regarding bringing down civilization. The bulk of the book is written by the other two authors and covers the history of effective militant resistance movements such as parts of the U.S. civil rights movement and the Movement for the Emancipation of the Niger Delta (MEND), while also outlining potential strategies for above- and below-ground resistance to civilization, termed Decisive Ecological Warfare.

After the publication of this book, the authors co-founded an organization by the same name. Aric McBay left the organization at the beginning of 2012, however, attributing his departure to the alleged cancellation of a transgender-inclusive policy by Derrick Jensen and Lierre Keith.[24] Deep Green Resistance has disputed this account, saying that the decision to restrict women's spaces was made by the women of DGR, and not by Derrick Jensen or Lierre Keith.[25]

In 2011, Jensen also published Dreams, which draws on the mythologies of ancient cultures and the wisdom of contemporary thinkers like Jack Forbes, Waziyatawin (a Dakota activist), Paul Stamets, and Stanley Aronowitz and is Jensen's challenge to the view that there is no knowledge outside that gained by science, and Truths Among Us, a thought-provoking collection of interviews with 10 leading writers, philosophers, teachers, and activists who argue against society’s belief that corporations and governments know what is best for the future.

Jensen convened the conferences "Earth at Risk", which were held in November 2010 and 2011 in San Francisco and Berkeley, CA, respectively, with presentations by D.J., Arundhati Roy, William Catton, Rikki Ott, Thomas Linzey, Gail Dines, Jane Caputi, Waziyatawin, Aric McBay, Stephanie McMillan, Lierre Keith, and Nora Barrows-Friedman, which were also published on DVD and as a book.

Jensen has written three novels: Lives Less Valuable; Songs of the Dead; and The Knitting Circle Rapist Annihilation Squad.

Derrick Jensen's views are broadly controversial. The radical magazine CounterPunch, in addition to publishing interviews with and articles written by Jensen, has also published commentaries by others who are critical of the potential for Jensen's philosophy to lead misinterpreting followers towards nihilism due to his "apocalyptic" warnings.[26][27]

The organization Deep Green Resistance (DGR), of which Jensen is a founding member, has been accused of transphobia in relation to its radical feminist advocacy.[28][29] DGR has denied this, stating merely "a difference of opinion about the definition of gender" with transgender activists; according to DGR's radical feminism, gender refers to a patriarchal caste system rather than an internal set of feelings.[30] Its members claim to be "critical of gender itself. We are not gender reformists—we are gender abolitionists."[31]Earth First!, another radical environmental organization, has dissociated from and criticized Jensen and DGR,[32] publishing an online article claiming that leaked private emails reveal Jensen's animosity towards trans people and anarchists.[33][note 1]

Jensen has rarely commented publicly on transgender politics, though, in his 2006 book Endgame, Jensen does briefly mention and even identify with transgender people, along with other marginalized groups, in a call for political solidarity.[35] In 2015, Jensen published a CounterPunch article explaining that he is criticized by trans activists primarily because he believes (cisgender) women should not be forced "to share their most intimate spaces with men.... I believe that women have the right to bathe, sleep, gather, and organize free from the presence of men," which his opponents have regarded as offensive towards transgender women.[36] Some have defended Jensen's stance on gender, lauding that he challenges "trans activists on their assertions that... their brain is 'female',"[37] on the basis of this being a problematically essentialist position.

1998: Second Prize in the category of small budget non-profit advertisements, as determined by the Inland Northwest Ad Federation, for the first ad in the "National Forests: Your land, your choice" series.

1995: Critics' Choice for one of America's ten best nature books of 1995, for Listening to the Land: Conversations About Nature, Culture, and Eros.[6]

^In the alleged "leaked emails," Jensen comments that DGR members were assaulted and violently threatened by transgender anarchist activists at an anarchist event. In the emails, Jensen condemns the fact that no anarchists intervened to help the DGR members, generally calls anarchists liars, and refers to a transwoman by saying "You are not a woman. You are a man who believes he is a woman."[34]

^Endgame, V.2, p. 829: "We are the oppressed. We are prisoners, family farmers, animal liberators, women, children, American Indians, blacks, Mexicans, poor whites, Asians, people of the Third World, the indigenous. We are lesbians, homosexuals, transgendered."